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| The knowledgebase is organized into different categories; please select a category that you are interested in. You can also search the entire knowledgebase by entering keywords in the navigation bar beside this text. |
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 | How much magnification and true field of view does the NexImage camera have when placed in my eyepiece holder? |  |
| The approximate magnification of an astronomical imaging camera is equivalent to that of an eyepiece with the same focal length in millimeters as the camera’s film or chip |
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| How do I connect a single-lens reflex (SLR) camera to my telescope? | |
| To connect an SLR camera to your telescope, you’ll need two accessories: a T-ring and a T-adapter. The T-adapter system is a worldwide standard 42mm thread to connect cameras to other devices. |
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| I’m using a focal reducer and can’t seem to focus my SLR camera on my Schmidt-Cassegrain telescope (SCT). What am I doing wrong? | |
| You may not have enough back focus with the focal reducer in place.A focal reducer is an accessory that screws onto the threads on th |
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| I’m doing photography with an eyepiece, using my camera with and without a lens. What are the f-numbers of my setup for the afocal and eyepiece projection methods? | |
| The afocal photographic method uses an eyepiece projecting through the camera’s lens and can be used with fixed lens (point and shoot) as well as removable lens (SLR) cameras. |
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| What is back focus? What problems does it cause for visual and photographic use of my scope? What are related focus issues? | |
| Back focus is the distance from the end of your eyepiece drawtube to the focal plane of your telescope. It varies greatly with the type of telescope. |
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| What is field rotation? How does it affect my scope’s viewing and imaging? |  |
| Field rotation is the apparent rotation of a celestial object in the field of view of a telescope during the course of the night. All objects in the eyepiece field or on the camera’s image will move in |
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| Why do I need to guide my telescope for photography? Don’t accurate alignment and firmware functions like periodic error correction (PEC) take care of it all? | |
| An excellent mount can greatly minimize the need for guiding and probably eliminate it for shorter exposures with shorter focal-length scopes or piggybacked cameras. |
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| I want to use the focal reducer/corrector with an aftermarket eyepiece holder. What is the best spacing, focal length, etc? | |
| Celestron’s focal reducer/corrector is optimized to change the focal ratios and effective focal lengths of f/10 Schmidt-Cassegrain telescopes (SCTs).A focal reducer is an accessory that scr |
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| What are Fastar and HyperStar? How do they work? | |
| Fastar is a system invented by Celestron in the 1990s to quickly and easily convert our Schmidt-Cassegrain telescope (SCT) f/10 optical tube assembly (OTA) into a very short focal length, fast f/2 imager. |
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| What is a radial guider? How does it help with astrophotography? | |
| A radial guider is a combination T-adapter and eyepiece that allows photography and guiding at the same time through your main scope. It fits on to a typical SCT in place of the visual back. It w |
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| What advantages does the Celestron zoom eyepiece #93230 have for SLR (DSLR) photography? | |
| A zoom eyepiece allows a wide range of magnifications for visual use.The same advantage is true when using one for photography, where |
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| How are file size and resolution related for digital cameras and imagers? | |
| The size of a file saved to a camera’s memory or transferred to a computer is related to the amount of information captured in the image by the camera., The camera image information capacity is usually |
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| I’m using a NexImage or CCD webcam on the planets and I notice that the image is soft or has a white glow that I can’t get rid of. What’s wrong? | |
| The good news is that nothing is wrong with your telescope. The additional glow or softening of contrast comes from infrared light sensitivity of the webcam’s chip and the way it separates |
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| My autoguider port seems to have a problem. How do I check it? | |
| Issue a command to move your mount from your autoguider program or autoguider hand control (not to be confused with the scope’s NexStar hand control).The movement is very small, so you ne |
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| What are the differences between training the PECTool visually with a crosshair eyepiece and training it with a CCD camera? | |
| None, really, other than it’s much easier and more accurate to let an autoguider program and CCD do the work and accumulate the PEC (periodic error correction) data. Many astronomical c |
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| I’m using my mount with an autoguider and getting mixed results. What are the best settings to use with Celestron mounts? | |
| There are no official settings to use with Celestron mounts that support autoguiders (these scopes have ports that will directly interface with any of the SBIG (Santa Barbara Instrument Group) type autoguide |
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| My autoguided exposures show trailing. What could cause this? | |
| Like any technology, autoguiders must work in the real world. In use, these are common situations of trailing or distorted images, along with their solutions.The stars appear to have moved in sho |
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| Is the Deluxe Tele-Extender #93643 compatible with my EdgeHD? | |
| The Deluxe Tele-Extender has two setscrews that are designed to lock the main body of the extension tube to the visual back or onto a projecting eyepiece or lens. One setscrew must b |
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| Will the Deluxe Tele-Extender #93643 work with any eyepiece or Barlow? | |
| The Deluxe Tele-Extender has two setscrews that are designed to lock the main body of the extension tube to the visual back or onto a projecting eyepiece or lens. One setscrew mu |
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| I want to autoguide with my Alt-Azimuth mount for long-exposure astrophotography. Will this work? | |
| Technically, yes, it will work. Many modern autoguiders can keep up with the guide rates involved. In practice, no, guiding with an alt-azimuth mount won’t work. Here’s why. |
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| When using my autoguider and /or autoguiding program, I’m not getting any motion when I’m calibrating it. Is there a problem with my mount’s autoguiding port? | |
| First, make sure you have the mount’s autoguiding rate set properly. This is found under SCOPE SETUP > AUTOGUIDING RATE in your hand control menu. Note that 00 is a rate |
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| What’s the best way to use my point-and-shoot camera with a telescope? | |
| Use a point-and-shoot digital camera with the Celestron #93626 universal digital camera adapter. Here the camera is held by the adapter behind the telescope’s eyepiece. Thi |
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| I have a Celestron GOTO scope, a Mac and an autoguider. I want to autoguide with the scope. Is your autoguider port Mac-compatible? | |
| For your autoguiding, it's only necessary that the autoguider and or its software itself be Mac-compatible. The signals to the scope from virtually all autoguiders are the SBIG S |
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| Can I use the NexGuide with a mount that only tracks in RA? | |
| Yes you can.Most mounts will have very little tracking error in Dec if properly polar-aligned.NexGuide has settings for |
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| What is seeing? How does it affect my observing and astrophotography? | |
| Seeing is the term astronomers use to describe the stability of the atmosphere for observing. Seeing significantly affect |
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| What do I need to know about mechanical backlash and guiding? | |
| Mechanical backlash is caused by static friction (also called stiction). It happens when your mount makes minor adjustments to its position in the same direction, stopping between each adjustm |
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| Can an old-style Celestron hand control be used to guide with my modern mount? | |
| Any of Celestron’s mounts with an autoguider port can use a push-button (momentary contact) hand control for manual guiding of the scope. |
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| What is the T-mount system? What are T-adapters and T-rings? | |
| The T-mount system uses T-threads of metric dimensions 42mm diameter and a pitch of 0.75mm to mate cameras to lenses and telescopes as well as other devices.T is for |
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| Can I control my Celestron GOTO mount with programs like Maxim DL? | |
| Yes you can.Such programs connect to the mount via ASCOM (AStronomy Common Object Model). ASCOM provides a standard interface for a range of astronomy equipment inclu |
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| What advantages does the Celestron zoom eyepiece #93232 have for SLR (DSLR) photography? | |
| A zoom eyepiece allows a wide range of magnifications for visual use.The same advantage is true when using one for photography, where |
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| Where can I find a smartphone adapter to take pictures with my scope? | |
| Please contact Orion Telescopes and check out their line of SteadyPix smartphone adapters: |
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| What is the difference between training and recording periodic error correction (PEC)? | |
| PEC is a means of reducing errors caused by the worm gear of the mount as it turns to drive the mount. In order to perform PEC, you must first inde |
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| What is the minimum pulse length required by the autoguiding ports on Celestron mounts? | |
| You should use pulses not less than 10 milliseconds (ms) in length. The autoguider port is polled approximately once per ms by the mo |
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